The present invention relates to the food packaging art, and more particularly to a sliding lid closure for a carton for packaging, storing and cooking food.
There is a considerable market for low cost, disposable cartons for packaging food wherein the cartons protect the food packaged therein during shipment and refrigeration, and additionally, may be used for heating and serving the food. Moreover, with the development of thermally stable polymers and paperboard for use in conventional and microwave ovens, disposable food packages prepared from such materials are finding increased popularity.
In general, cartons of the class described and disclosed in the prior art comprise trays or the like which may be prepared on high speed forming equipment. some of these trays include integral closure tops, but most utilize separate closure members that in most cases are adhered to a flange element around the upper edge of the tray. In at least one instance, as shown in British Pat. No. 1,384,547, a lid is provided for a flanged tray which includes side panels that extend downwardly to enclose the sides of the tray. Applicant's prior art patent, U.S. Pat. No. 4,190,191 shows another more typical example of a sliding lid for a flanged tray. Meanwhile, there are few if any teachings in the prior art for sliding lids on trays without flanges. Where the tray does not include an upper or top flange, some other means is required for retaining the lid on the tray.
U.S. Pat. No. 3,314,585 shows a combination lid and tray wherein the end portions of the lid are tucked behind notches provided in the tray side walls. U.S. Pat. No. 3,504,843 shows a sliding lid for a container wherein the outermost edges of the lid are folded around slots provided at the front and rear of the container for holding the lid on the container. Further, U.S. Pat. No. 4,076,168 discloses a carton for food products wherein the lid and tray include integral flange portions which are stapled together. Thus, although the prior art teaches the concept of lids for open top trays without a flange, there is no clear showing of a sliding lid for a tray havig tapered side walls and no integral upper or top flange.